Police also noted that, though Berezovsky has been named, the formal identification process would not be completed until Tuesday.

Earlier police said the area around the estate would remain sealed off "until Wednesday or Thursday in order to protect the scene." An earlier search for evidence of radiation or chemicals returned up negative.

Berezovsky made his fortune selling luxury cars and later founded Moscow’s first independent television station in the tumultuous times after Russia privatized state assets in the 1990s.

He helped orchestrate the re-election of Boris Yeltsin in 1996 and also played a role in Vladimir Putin's rise to power. Berezovsky, however, fell out of favor when Putin became president in 2000 — and became one of the strongman’s critics.